1. Field of the Invention
The present invention relates to a hydrodynamic bearing assembly and a motor including the same, and more particularly, to a hydrodynamic bearing assembly and a motor including the same, in which a stopper ring is set to protrude from a stopper ring housing portion to increase the flatness of the stopper ring, when welding the stopper ring for fixing a thrust plate and the stopper ring housing portion of a sleeve which is stepped for housing the stopper ring.
2. Description of the Related Art
Small-sized spindle motors used in recording disc driving devices are being applied to various portable products such as netbooks, mobile phones, portable multimedia players (PMP), game machines, and MP3 players.
Recently, as the performance of recording disc driving devices has improved, demand for low current, low Non Repeatable Run Out (NNRO), impact resistance, and vibration resistance has rapidly increased in the field of spindle motors used in the driving devices.
Meanwhile, when press-processed parts are assembled into a motor, laser welding may be applied in order to ensure good oil sealing characteristics, bonding strength, and convenience of assembling operation.
However, press-processed parts have low level precision and are affected by expansion and contraction caused by heat during a welding process, and may generate residual stress.
In particular, when a stopper ring for fixing a press-processed thrust plate is disposed in a stopper ring housing portion of a sleeve to perform welding, a gap may be formed between the stopper ring housing portion and the stopper ring due to a round portion formed on an outer circumference of the stopper ring disposed inside the stopper ring housing portion. In this case, poor quality welds may occur.
Furthermore, the stopper ring may be raised from the stopper ring housing portion, as the welding material hardens. In this case, after welding, the flatness of the upper surface of the stopper ring may be degraded.